Jaap Sombroek joined Dutch band BZN to replace initial drummer Gerrit Woestenburg. In 1968 Sombroek departed to join Left Side (where he replaced Jaap Kras). Jaap Sombroek was replaced by Jan Keizer (ex-Q-Tips).



Jaap Sombroek parted ways with Left Side and went to Next One in 1974. Sombroek was replaced by Klaas Tuyp.